1. Lab. (7) Bacterial colony morphology
الجامعة الإسلامية-غزة
كلية العلوم الصحية
قسم العلوم الطبية المخبرية
Lab. (7) Bacterial colony morphology

2. Introduction
Bacteria grow on solid media as colonies. A colony is defined as a visible mass of microorganisms all originating from a single mother cell, therefore a colony constitutes a clone of bacteria all genetically alike.
In the identification of bacteria and fungi much weight is placed on how the organism grows in or on media.
Colony morphology : Examination of the form and structure(cultural characteristics) of bacterial colonies on an agar plate.
Features of the colonies may help to pinpoint the identity of the bacterium. Different species of bacteria can produce very different colonies. 

3. Colony morphology Shape Size Margin/edge Elevation/height Color
Texture /consistency
Appearance
Optical property/ opacity

4. Colony shape Shape refers to the overall appearance of the colonies.
The descriptors here are circular, irregular, filamentous (has individual thin projections), rhizoid (has thin, branching projections), or spindle (lens-shaped).

5. Colony size Colony size depend on: The growth medium
The number of colonies present on a plate
punctiform
small
medium
large

6. Colony margin/edge
The margin or edge of a colony may be  an important characteristic in identifying an organisms.
Common examples are Entire (smooth), irregular, Undulate (wavy), Lobate, Curled, Filiform etc.
Colonies that are irregular in shape and/or have irregular margins are likely to be motile organisms. Highly motile organism swarmed over the culture media. Such as Proteus spp

7. Colony elevation/height
It is description of how the colony grows vertically.
Colonies may be flat, raised, umbonate (having a knobby protuberance), Crateriform, Convex, Pulvinate (Cushion-shaped)

8. Colony color/pigmentation
Some bacteria produce pigment when they grow in the medium e.g., green pigment produces by Pseudomonas aeruginosa,  buff colored colonies of Mycobacterium tuberculosis on L.J medium, red colored colonies of Serratia marcescens.

9. Consistency/texture
Several terms that may be appropriate for describing the texture or consistency of bacterial growth  are: dry, moist, viscid (sticks to loop, hard to get off), brittle/friable (dry, breaks apart), mucoid (sticky, mucus-like)

10. Appearance of the colony surface
Bacterial colonies are frequently shiny and smooth in appearance. Other surface descriptions might be: dull (opposite of glistening), veined, rough, wrinkled (or shriveled), glistening.

11. Optical property/opacity
Is the colony transparent (clear), opaque (not transparent or clear), translucent (almost clear, but distorted vision–like looking through frosted glass), iridescent (changing colors in reflected light).

15. Stereoscopic microscope a binocular microscope modified  to give a three-dimensional view of the specimen.
Objectives:
Describe features of colonies.
See variations in colonial morphology among various species of bacteria. 
Materials needed:
agar plates of various bacteria (Micrococcus, Bacillus,, Streptococci, Staphylococci, E. coli, Pseudomonas, B. cereus, and B. subtilus).

16. Procedures:
Use a plate which has well-isolated colonies. Look at the largest colonies with the naked eye to determine general shape and chromogenesis.
Use a dissecting/stereoscopic microscope for more detail. Place the plate rightside up on the stage, leaving the petri dish cover ON (Otherwise, your culture will become contaminated.) There are 2 lenses on our scopes—10X and 20X: the black lens knob is on the right side of the head of the microscope. The magnification is especially helpful for the study of elevation, surface, opacity, size, and edge. There are 2 lights on these microscopes that you might find helpful, either using one at a time, or both, or even sometimes without them. Two small black rotating knobs on either side of the base control the 2 lights, one light from above and one light from below the stage.

17. If you see water condensation on the lid cover, take a KimWipe and carefully remove the water from the cover, then quickly replacing the cover on the dish.
In order to determine consistency, you need to use your inoculating loop or needle to pick up the colony and determine the consistency of the inoculum material as the loop leaves the agar medium.

18. Staphylococcus aureus
Description
Result
Colony shape
Circular form
Colony margin
Entire margin
Optical property
Opaque
Colony elevation
Convex
Colony color ( pigment )
Golden yellow color
Colony surface
Smooth
Staphylococcus aureus

19. Description Result Serratia marcescens Colony shape Circular form
Colony margin
Entire margin
Optical property
Opaque
Colony elevation
Convex
Colony color ( pigment )
Red color
Colony surface
Smooth
Serratia marcescens

20. Streptococcus pneumoniae
Description
Result
Colony shape
Circular form
Colony margin
Entire margin
Optical property
Opaque
Colony elevation
Raised
Colony color ( pigment )
White color
Colony surface
Smooth
Streptococcus pneumoniae

21. Description Result Colony shape Circular form Colony margin
Entire margin
Optical property
Opaque
Colony elevation
convex
Colony color ( pigment )
white color
Colony surface
Smooth

22. Description Result Colony shape Circular form Colony margin
Entire margin
Optical property
Opaque
Colony elevation
Umbonate
Colony color ( pigment )
Red color
Colony surface
Smooth

23. Description Result Colony shape Filamentous form Colony margin
Filiform margin
Optical property
Opaque
Colony elevation
Weak convex
Colony color ( pigment )
White color
Colony surface
Wrinkled

24. Description Result Colony shape Filamentous form Colony margin
Filiform margin
Optical property
Opaque
Colony elevation
Weak Umbonate
Colony color ( pigment )
Beige color
Colony surface
Wrinkled

25. Description Result Colony shape Irregulare form Colony margin
Undulate margin
Optical property
Opaque
Colony elevation
Weak Umbonate
Colony color ( pigment )
White color
Colony surface
Smooth

26. Description Result Colony shape Weak Irregular Colony margin
Undulate margin
Optical property
Opaque
Colony elevation
Weak Umbonate
Colony color ( pigment )
White color
Colony surface
Smooth

27. Description Result Colony shape Irregular form Colony margin
Lobate margin
Optical property
Opaque
Colony elevation
Weak Umbonate
Colony color ( pigment )
Yellowish color
Colony surface
Smooth

28. Description Result Colony shape Circular form Colony margin
Entire margin
Optical property
Opaque
Colony elevation
Pulvinate
Colony color ( pigment )
Black color
Colony surface
Smooth

29. Description Result Colony shape Circular form Colony margin
Entire margin
Optical property
Opaque
Colony elevation
Weak Umbonate
Colony color ( pigment )
Red color
Colony surface
Smooth

30. Description Result Colony shape Circular form Colony margin
Entire margin
Optical property
Opaque
Colony elevation
Umbonate
Colony color ( pigment )
Grayish color
Colony surface
Smooth

31. Mycobacterium tuberculosis
Description
Result
Colony shape
Irregular form
Colony margin
Undulate margin
Optical property
Opaque
Colony elevation
Pulvinate
Colony color ( pigment )
Yellow color
Colony surface
Rough
Mycobacterium tuberculosis

32. Description Result Colony shape Rhizoid form Colony margin
Filiform margin
Optical property
Opaque
Colony elevation
Raised
Colony color ( pigment )
White color
Colony surface
Rough

33. Pseudomonas aeruginosa
Description
Result
Colony shape
Circular form
Colony margin
Entire margin
Optical property
Opaque
Colony elevation
Flat
Colony color ( pigment )
Gray color
Colony surface
Smooth
Pseudomonas aeruginosa